Drought stretches irrigation to limits

Paul L. Hollis | Oct 18, 2000

"I'll just be glad when it's over." This sentiment, spoken recently by east Alabama cotton producer Harris Sistrunk, is being echoed in cotton fields throughout the lower Southeast, as growers assess the damage from one of the worst droughts on record.

"We had to water the cotton up to a stand this year," said Sistrunk during an east Alabama cotton tour. "Irrigation is great, but it's not a substitute for rain. Our cotton should look better than this - we just didn't get any rainfall."

Sistrunk estimates that his irrigated cotton has received about 12 or 13 applications this season, putting on three-fourths to one and a half inch each time. "We've been watering all day, every day, and we still haven't been able to keep up. We've got irrigation on about 800 acres of cotton, and we've kept it wet. But several consecutive days of 100-degree temperatures just destroyed some of it," he says.

Sistrunk normally averages between 750 and 850 pounds of cotton per acre, including his dryland acreage. "My goal when I first put in irrigation was to make more than a bale and a half every year, and I don't think we've made less than 1,000 pounds on our irrigated acreage.

"I'm pretty sure this year's crop will pay the bills. But I've got more bills and a little less cotton than usual."

Like other growers who have witnessed the stark difference between irrigated and non-irrigated crops, Sistrunk is considering expanding his irrigation capability for 2001, possibly by adding three more center pivots.

The situation for Alabama farmers with irrigation this year varied widely, says Larry Curtis, Auburn University Extension engineer. There were reports of water sources drying up in south Alabama's Wiregrass Region, and most growers with irrigation were forced to water from planting up until harvest.

"In a typical year, we've felt that eight to 12 inches of water is sufficient for a cotton crop. But this year was unusual in that we were forced to irrigate from planting until harvest, supplying all of the plant's water needs. Some growers put on as much as 18 inches of water this year.

"Last year, we put 12 inches of water on our plots at Belle Mina in north Alabama, and we thought that was as bad as it could get. This year, we put on more than 15 inches. In a year like this, we had to put on all of the water that the crop could utilize, and that gets up to about 20 inches," says Curtis.

Many growers, especially those with older irrigation systems, couldn't catch up with watering this year, he adds. "Some growers have systems that are under-sized and don't have the ability to meet the evapotranspiration needs of the crop. Those systems got behind this year because they didn't get any relief from rainfall.

"Ideally, we'd like to have rainfall to augment our irrigation. This allows our systems to catch up, and it refills the soil moisture reservoir. That didn't occur this year. We'll see some drop off in yields this year where the systems couldn't meet the maximum evapotranspiration needs of the crop," notes the engineer.

There's a tendency, especially in years with normal rainfall, for growers with irrigation not to run their systems as often as needed, says Curtis.

"During the peak water-use period for cotton, we need to be putting on two inches per week. The key to good irrigation scheduling is that if you get a good rain or wet period, you need to start back watering before you think you need to. In a drought situation, it's a good idea to start early and put out less water in the beginning and then increase the amount of water as the season progresses."

As some growers in south Alabama depleted their water sources this year, there was talk of long-term solutions to the water shortage, including building reservoirs.

"There are rivers and streams in south Alabama that would lend themselves to dam projects, but there are a tremendous amount of obstacles to overcome, and a tremendous amount of money to be raised before such projects could become a reality.

"You must have eminent domain in those drain spaces, and that could include a huge amount of land. There also would be concerns about damming creeks and rivers and the resulting effects on endangered species or wetlands."

Once the water is dammed, a distribution system will be required to get water from the reservoir to the farms, says Curtis, and this could cost from $1,000 to $1,500 per acre.

"I can't imagine that such a project could be done even in a 10-year time frame. It would take about 20 years to be completed, and that wouldn't make a difference for most of our farmers. In addition, huge grants would be required to finance such a project, and I don't know where we would get those resources."

Groundwater is available in most regions of the state, but it's very expensive to develop, especially in south Alabama, he adds.

"If a grower already is mortgaged to the hilt, he won't be able to pull himself out of debt by adding irrigation. I've rarely seen a case where irrigation saved a farmer who is deeply in debt and in a desperate situation.

"Irrigation tends to work best for those growers who have a stable economic situation. Irrigation will stabilize yields at a higher level. And crops respond to irrigation, especially in a dry year. Irrigation does, however, require more work and commitment from the grower to run the systems and manage the water resources.'